Dopamine & Serotonin: Functions & Relationship

Instructor: Veronika Polozkova

Masters in International Health. Lesson development experience on different levels from basic alimentary school to academic master level. Languages: English, Dutch, Russian

Dopamine and serotonin are often called the happy chemicals in popular blogs and websites. But it is not that simple. Do you want to know what they really are? Find out in this lesson!

What are Dopamine and Serotonin?

Dopamine and serotonin are both neurotransmitters. Neurotransmitters are chemicals that are released from the nerve cells and serve to transfer impulses from nerve cells to other body tissues like other nerve cells, muscles, and organs. These chemicals are very important in sensual perceptions and motoric action-reaction mechanisms.

Neurotransmitters transfer nerval impulses through the body


Dopamine plays an important role in controlling motor behavior, the emotional reward, and behavior motivation mechanisms. It regulates emotional responses, hormone secretion, and motoric actions related to reward sensations. Most types of rewards increase dopamine levels in the brain and cause satisfied feelings, which serves as motivation to perform the behavior in the future.

Deficiency in dopamine leads to reduced motoric function, which can lead to Parkinson disease. Low dopamine levels are also associated with low motivation, vulnerability for addictions, and the addiction mechanism itself. The last has to do with the fact that many addictive substances (alcohol and drugs) and behaviors (shopping and gambling) increase dopamine levels in the brain temporarily, stimulating the feeling of satisfaction. This mechanism can force someone to use a substance again or repeat other addictive behavior in order to re-experience that emotionally positive sensation, thereby playing a huge role in the recurring drug use that leads to addiction. Very high dopamine levels are linked to mental disorders like schizophrenia, which among other things is characterized by unrealistic perceptions of a situation and emotional arousal.


Serotonin regulates the functioning of the cardiovascular and endocrine systems and has an important role in regulating appetite, sleep, memory, mood, body temperature, and muscle contraction. About 90% of serotonin is found in the intestine, with the remaining 10% in the central nervous system. Low serotonin levels are associated with insomnia (sleepless nights), decreased empathy, anxiety disorders, memory and learning impairment, mood changes, and depression.

Abnormally high serotonin levels are not common, but do occur in people who are being treated for depression with medications (like SSRI's) or supplements that increase serotonin levels. Common symptoms for high serotonin levels are sweating, elevated heartbeat, restlessness, mania, hot and cold flashes, and weight gain.

Dopamine and Serotonin Interactions

As you can see from the functions listed above, both dopamine and serotonin play an important role in human behavior and emotions, but both affect people in different ways and through different physiological paths. In popular language and many blogs those two chemical elements are often called the 'happy chemicals'. But the reality is not that simple, because they function through different mechanisms and also because they can interact with each other and give mutually reinforcing or contradicting effects.

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